1. Field of the Invention
The present invention relates to an image-forming apparatus used for performing an image formation operation on a recording medium (a printing medium), especially using a cloth as the recording medium. More specifically, the invention relates to a fluid-ejecting apparatus employing an ink-jet printing head for ejecting a fluid, such as ink, onto the cloth to perform textile printing. Furthermore, the present invention also relates to an information-processing system, such as a textile-printing system, using such apparatus as an output device.
2. Description of the Related Art
Heretofore, an ink-jet recording method has been used in output means of data-processing systems. The output means have been provided as printers, as output terminals of copying machines, facsimile machines, printing machines, word processors, work stations, or the like, or provided as handy- or portable printers, for personal computers, host computers, optical disc- or video-equipment, or the like. The ink-jet recording method comprises the step of forming an image of input data of characters, pictures, drawings or the like on a recording medium (e.g., a sheet of paper, an OHP sheet, or a cloth) by directly ejecting minute ink droplets from minute nozzles. Therefore, the ink-jet recording method has several advantages over the others in that it provides excellent image qualities and performs high-speed printing. In addition, a recording apparatus using the ink-jet recording method (hereinafter, also referred to as an ink-jet recording apparatus) is of a non-impact type, so that it performs printing without causing unpleasant noise. Besides, it easily performs full-color printing by using different color inks. Furthermore, it is easy to down size the ink-jet recording apparatus and also it is easy to provide high-density images by using such apparatus.
Accordingly, the ink-jet recording method can be applied not only in the field of data-processing but also extensively in fields using an ink-supporting medium (e.g., a sheet of paper, an OHP sheet, or a cloth) to be given ink or the like, such as the textile and clothing industries.
In the textile field and the clothing industries, the ink-jet method can be used in a textile-printing system comprising an ink-jet fluid-ejecting apparatus (a textile-printing apparatus) as an output device. The ink-jet textile-printing apparatus has several advantages over the others in that it performs image-printing with more complete control and with a lower total cost because it does not require a negative plate of an image to be printed. In the case of screen-printing, on the other hand, a costly plate can be required and the printing can be performed beyond the limits.
One of the conventional ink-jet textile-printing apparatuses is disclosed in Japanese Patent Application Laid-open No. 212851/1993. In FIG. 2 of the reference, the textile-printing apparatus comprises a printer unit having nozzle heads and a transport mechanism for transporting a recording medium, such as a cloth. The nozzle head ejects ink droplets against the cloth to be transported in the vertical direction to print an image thereon. That is, the nozzle head ejects ink droplets in the horizontal direction. In the area in which printing is performed by ejecting ink droplets, the printer unit, having the nozzle heads, is mounted so as to face the transport mechanism having an endless belt. In this case, the fabric is provided at a location between them. In general, furthermore, the printer unit is mounted in the textile-printing apparatus so as to smoothly move in the horizontal direction and also so as to shift its position or the like to make it possible to adjust the distance between the unit and the fabric or to replace the endless belt. In general, by the way, it is natural that the printing devices should be improved so as to print images on the recording medium at a higher speed, not excepting the ink-jet textile-printing apparatus, as a logical consequence.
For directly realizing high-speed printing on a fabric having a relatively long length and width or on a long cloth continuously provided by the transport mechanism, there is an attempt to increase the number of orifices arranged on the ink-jet head. In this case, it can be achieved by setting a long-sized head. That is, it means that the long-sized head extends in the direction of transporting the recording medium, such as a cloth, and comprises an increased number of the orifices arranged in that direction. Therefore, the width of one line to be printed by one scanning movement of the long-sized head is greater than that of a normal one. In general, the distance of shifting the recording medium by the transporting mechanism corresponds to a width of a line to be recorded, so that the printing speed can be improved by increasing the above distance in accordance with the line's width.
In the case of the textile-printing apparatus, as disclosed in the above reference, the long-sized printing head leads to a comparatively great difference among the water heads of the orifices because these orifices are arranged in the vertical direction. It is noted that such difference leads to a different volume of an ink droplet to be ejected from each orifice, resulting in the deterioration of image-qualities.
In the case of the textile-printing apparatus, as disclosed in Japanese Patent Application Laid-Open No. 31905/1993, on the other hand, a printing head is installed in the device so as to eject ink droplets vertically from a higher to a lower place. In this case, therefore, the orifices are arranged in a horizontal direction, so that there is no difference among their water heads in general, thereby avoiding the problem.
Furthermore, the above recording head facing downward has an effect on the ability to recover ejected ink droplets from each orifice by absorbing ink therefrom or by other means. In addition, it also has an effect on preventing a water drop, attached on an ejection surface of the recording head, from entering into the orifice.
In spite of the above advantages, the printing apparatus, having a printing head facing downward without any improvement may cause several troubles as a result of its particular configuration.
For the conventional textile-printing apparatus, a head-recovering means using a wash fluid can be employed because the concentration of dye in the ink being specified for the print is higher than that of the ink used in the other kind of the image-forming apparatus. In textile-printing, the specified dye is easily precipitated by evaporating the water content of the ink. Japanese Patent Application Laid-Open No. 79880/1994 discloses an ink-jet textile-printing apparatus employing one of the conventional examples of the above means. In the reference, the recovery of ejected ink droplets of an ink-jet printing head can be performed by the excellent recovering means. That is, the recovering means performs a process that comprise the steps of: washing a cleaning blade made of a porous material by dropping wash fluid (i.e., wash water); sucking the wash water absorbed in the blade by a suction pump; and wiping off the ink-jet printing head to prevent the above dye precipitation. In the case that the printing head is installed in the device so as to front on downward, a longitudinal direction of the printing head is horizontally arranged. In the same way as the other conventional constructions, therefore it is difficult to wash a whole surface of the cleaning blade elongated in the longitudinal direction by the wash fluid dropping from a single nozzle. In the conventional device, furthermore, it is also difficult to wash the whole surface of the cleaning blade because of uneven running of the wash fluid. Conventionally, therefore, the conventional printing apparatus has been complicated in structure because of several attempts to avoid the above problem, by providing a plurality of nozzles for running the wash fluid on the blade in the longitudinal direction thereof, and moving the nozzles along the blade in the predetermined direction. In proportion to the length of the ink-jet head and the cleaning blade, furthermore, the attempts lead to the growing use of wash water and result in a rising cost of running the device. That is, the rate of running the wash water may be almost 10 cubic centimeter per 3 seconds for washing a head of 16 mm in print width. In spite of the great quantity of wash water, only a part thereof substantially contributes to remove dirty materials from the blade.
Accordingly, there has been a demand for a novel fluid-ejecting apparatus which is able to wash a cleaning blade easily and perfectly with a smaller use of the wash water, and also a novel information-processing system, such as a textile-printing system using such apparatus as an output printing means.